/**************************************************************************
 *
 * Copyright (C) 2016 Steve Karg
 *
 * SPDX-License-Identifier: GPL-2.0-or-later WITH GCC-exception-2.0
 *
 *********************************************************************/
#include <stdio.h>
#include <stdlib.h>
#include <stdint.h> /* for standard integer types uint8_t etc. */
#include <stdbool.h> /* for the standard bool type. */
#include "bacnet/bacdcode.h"
#include "bacnet/config.h"
#include "bacnet/basic/sys/debug.h"
#include "bacnet/basic/object/device.h"
#include "bacnet/basic/bbmd6/h_bbmd6.h"
#include "bacnet/datalink/bip6.h"
#include "bacport.h"

/* Win32 Socket */
static SOCKET BIP6_Socket = INVALID_SOCKET;
static int BIP6_Socket_Scope_Id = 0;
/* local address - filled by init functions */
static BACNET_IP6_ADDRESS BIP6_Addr;
static BACNET_IP6_ADDRESS BIP6_Broadcast_Addr;

/* enable debugging */
static bool BIP6_Debug = false;

/**
 * @brief Print the IPv6 address with debug info
 * @param str - debug info string
 * @param addr - IPv6 address
 */
static void debug_print_ipv6(const char *str, const struct in6_addr *addr)
{
#if PRINT_ENABLED
    char addstr[40] = { 0 };
    BACNET_IP6_ADDRESS bip6_addr = { 0 };

    if (str && addr) {
        memcpy(&bip6_addr.address[0], &addr->s6_addr[0], IP6_ADDRESS_MAX);
        bvlc6_address_to_ascii(&bip6_addr, addstr, sizeof(addstr));
        if (BIP6_Debug) {
            debug_fprintf(stdout, "BIP6: %s %s\n", str, addstr);
        }
    }
#endif
}

/**
 * @brief Enabled debug printing of BACnet/IPv4
 */
void bip6_debug_enable(void)
{
    BIP6_Debug = true;
}

static LPSTR PrintError(int ErrorCode)
{
    static char Message[1024];

    /* If this program was multithreaded, we'd want to use
       FORMAT_MESSAGE_ALLOCATE_BUFFER instead of a static buffer here.
       (And of course, free the buffer when we were done with it) */

    FormatMessage(
        FORMAT_MESSAGE_FROM_SYSTEM | FORMAT_MESSAGE_IGNORE_INSERTS |
            FORMAT_MESSAGE_MAX_WIDTH_MASK,
        NULL, ErrorCode, MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),
        (LPSTR)Message, 1024, NULL);
    return Message;
}

/* on Windows, ifname is the IPv6 address of the interface */
void bip6_set_interface(char *ifname)
{
    int i, RetVal;
    struct addrinfo Hints, *AddrInfo, *AI;
    struct sockaddr_in6 *sin;
    SOCKET ServSock[FD_SETSIZE] = { 0 };
    char port[6] = "";
    int sockopt = 0;

    /* By setting the AI_PASSIVE flag in the hints to getaddrinfo, we're
       indicating that we intend to use the resulting address(es) to bind
       to a socket(s) for accepting incoming connections.  This means that
       when the Address parameter is NULL, getaddrinfo will return one
       entry per allowed protocol family containing the unspecified address
       for that family. */
    memset(&Hints, 0, sizeof(Hints));
    Hints.ai_family = AF_INET6;
    Hints.ai_socktype = SOCK_DGRAM;
    Hints.ai_protocol = IPPROTO_UDP;
    Hints.ai_flags = AI_NUMERICHOST | AI_PASSIVE;
    snprintf(port, sizeof(port), "%u", (unsigned)BIP6_Addr.port);
    if (BIP6_Debug) {
        debug_fprintf(
            stderr, "BIP6: seeking IPv6 address %s port %s...\n", ifname, port);
    }
    RetVal = getaddrinfo(ifname, &port[0], &Hints, &AddrInfo);
    if (RetVal != 0) {
        debug_fprintf(
            stderr, "BIP6: getaddrinfo failed with error %d: %s\n", RetVal,
            gai_strerror(RetVal));
        WSACleanup();
        return;
    }
    if (BIP6_Debug) {
        debug_fprintf(stderr, "BIP6: getaddrinfo() succeeded!\n");
    }
    /* Find the first matching address getaddrinfo returned so that
       we can create a new socket and bind that address to it,
       and create a queue to listen on. */
    for (i = 0, AI = AddrInfo; AI != NULL; AI = AI->ai_next) {
        /* Highly unlikely, but check anyway. */
        if (i == FD_SETSIZE) {
            debug_fprintf(
                stderr,
                "BIP6: getaddrinfo returned more addresses than we could "
                "use.\n");
            break;
        }
        /* only support AF_INET6. */
        if (AI->ai_family != AF_INET6) {
            continue;
        }
        /* only support SOCK_DGRAM. */
        if (AI->ai_socktype != SOCK_DGRAM) {
            continue;
        }
        /* only support IPPROTO_UDP. */
        if (AI->ai_protocol != IPPROTO_UDP) {
            continue;
        }
        BIP6_Socket = socket(AF_INET6, SOCK_DGRAM, IPPROTO_UDP);
        if (BIP6_Socket == INVALID_SOCKET) {
            debug_fprintf(
                stderr, "BIP6: socket() failed with error %d: %s\n",
                WSAGetLastError(), PrintError(WSAGetLastError()));
            continue;
        }
        sin = (struct sockaddr_in6 *)AI->ai_addr;
        if ((AI->ai_family == AF_INET6) &&
            IN6_IS_ADDR_LINKLOCAL(&sin->sin6_addr) &&
            (sin->sin6_scope_id == 0)) {
            debug_fprintf(
                stderr, "BIP6: IPv6 link local addresses needs a scope ID!\n");
        }
        BIP6_Socket_Scope_Id = if_nametoindex(ifname);
        /* Allow us to use the same socket for sending and receiving */
        /* This makes sure that the src port is correct when sending */
        sockopt = 1;
        RetVal = setsockopt(
            BIP6_Socket, SOL_SOCKET, SO_REUSEADDR, (char *)&sockopt,
            sizeof(sockopt));
        if (RetVal < 0) {
            closesocket(BIP6_Socket);
            BIP6_Socket = INVALID_SOCKET;
            debug_fprintf(
                stderr,
                "BIP6: setsockopt(SO_REUSEADDR) failed with error %d: %s\n",
                WSAGetLastError(), PrintError(WSAGetLastError()));
            continue;
        }
        /* allow us to send a broadcast */
        RetVal = setsockopt(
            BIP6_Socket, SOL_SOCKET, SO_BROADCAST, (char *)&sockopt,
            sizeof(sockopt));
        if (RetVal < 0) {
            closesocket(BIP6_Socket);
            BIP6_Socket = INVALID_SOCKET;
            debug_fprintf(
                stderr,
                "BIP6: setsockopt(SO_BROADCAST) failed "
                "with error %d: %s\n",
                WSAGetLastError(), PrintError(WSAGetLastError()));
            continue;
        }
        bip6_join_group();
        /* bind() associates a local address and port combination
           with the socket just created. This is most useful when
           the application is a server that has a well-known port
           that clients know about in advance. */
        if (bind(BIP6_Socket, AI->ai_addr, AI->ai_addrlen) == SOCKET_ERROR) {
            debug_fprintf(
                stderr, "BIP6: bind() failed with error %d: %s\n",
                WSAGetLastError(), PrintError(WSAGetLastError()));
            closesocket(ServSock[i]);
            continue;
        } else {
            sin = (struct sockaddr_in6 *)AI->ai_addr;
            bvlc6_address_set(
                &BIP6_Addr, ntohs(sin->sin6_addr.u.Word[0]),
                ntohs(sin->sin6_addr.u.Word[1]),
                ntohs(sin->sin6_addr.u.Word[2]),
                ntohs(sin->sin6_addr.u.Word[3]),
                ntohs(sin->sin6_addr.u.Word[4]),
                ntohs(sin->sin6_addr.u.Word[5]),
                ntohs(sin->sin6_addr.u.Word[6]),
                ntohs(sin->sin6_addr.u.Word[7]));
            debug_print_ipv6("bind() succeeded!", &sin->sin6_addr);
            /* https://msdn.microsoft.com/en-us/library/windows/desktop/ms740496(v=vs.85).aspx
             */
        }
        i++;
        if (BIP6_Socket != INVALID_SOCKET) {
            break;
        }
    }
    freeaddrinfo(AddrInfo);
    if (BIP6_Socket == INVALID_SOCKET) {
        debug_fprintf(
            stderr, "BIP6: AF_INET6 address not found getaddrinfo()\n");
    }
}

/**
 * Set the BACnet IPv6 UDP port number
 *
 * @param port - IPv6 UDP port number
 */
void bip6_set_port(uint16_t port)
{
    BIP6_Addr.port = port;
    BIP6_Broadcast_Addr.port = port;
}

/**
 * Get the BACnet IPv6 UDP port number
 *
 * @return IPv6 UDP port number
 */
uint16_t bip6_get_port(void)
{
    return BIP6_Addr.port;
}

/**
 * Get the BACnet broadcast address for my interface.
 * Used as dest address in messages sent as BROADCAST
 *
 * @param addr - IPv6 source address
 */
void bip6_get_broadcast_address(BACNET_ADDRESS *addr)
{
    if (addr) {
        addr->net = BACNET_BROADCAST_NETWORK;
        addr->mac_len = 0;
        addr->len = 0;
    }
}

/**
 * Get the IPv6 address for my interface. Used as src address in messages sent.
 *
 * @param addr - IPv6 source address
 */
void bip6_get_my_address(BACNET_ADDRESS *addr)
{
    uint32_t device_id = 0;

    if (addr) {
        device_id = Device_Object_Instance_Number();
        bvlc6_vmac_address_set(addr, device_id);
    }
}

/**
 * Set the BACnet/IP address
 *
 * @param addr - network IPv6 address
 */
bool bip6_set_addr(const BACNET_IP6_ADDRESS *addr)
{
    return bvlc6_address_copy(&BIP6_Addr, addr);
}

/**
 * Get the BACnet/IP address
 *
 * @return BACnet/IP address
 */
bool bip6_get_addr(BACNET_IP6_ADDRESS *addr)
{
    return bvlc6_address_copy(addr, &BIP6_Addr);
}

/**
 * Determine if the BACnet/IPv6 address matches our own address
 *
 * @param addr - network IPv6 address
 *
 * @return true if the BACnet/IPv6 address matches our own address
 */
bool bip6_address_match_self(const BACNET_IP6_ADDRESS *addr)
{
    return !bvlc6_address_different(addr, &BIP6_Addr);
}

/**
 * Set the BACnet/IP address
 *
 * @param addr - network IPv6 address
 */
bool bip6_set_broadcast_addr(const BACNET_IP6_ADDRESS *addr)
{
    return bvlc6_address_copy(&BIP6_Broadcast_Addr, addr);
}

/**
 * Get the BACnet/IP address
 *
 * @return BACnet/IP address
 */
bool bip6_get_broadcast_addr(BACNET_IP6_ADDRESS *addr)
{
    return bvlc6_address_copy(addr, &BIP6_Broadcast_Addr);
}

/**
 * The send function for BACnet/IPv6 driver layer
 *
 * @param dest - Points to a BACNET_IP6_ADDRESS structure containing the
 *  destination address.
 * @param mtu - the bytes of data to send
 * @param mtu_len - the number of bytes of data to send
 *
 * @return Upon successful completion, returns the number of bytes sent.
 *  Otherwise, -1 shall be returned to indicate the error.
 */
int bip6_send_mpdu(
    const BACNET_IP6_ADDRESS *dest, const uint8_t *mtu, uint16_t mtu_len)
{
    struct sockaddr_in6 bvlc_dest = { 0 };
    uint16_t addr16[8];

    /* assumes that the driver has already been initialized */
    if (BIP6_Socket == INVALID_SOCKET) {
        return 0;
    }
    /* load destination IP address */
    bvlc_dest.sin6_family = AF_INET6;
    bvlc6_address_get(
        dest, &addr16[0], &addr16[1], &addr16[2], &addr16[3], &addr16[4],
        &addr16[5], &addr16[6], &addr16[7]);
    bvlc_dest.sin6_addr.u.Word[0] = htons(addr16[0]);
    bvlc_dest.sin6_addr.u.Word[1] = htons(addr16[1]);
    bvlc_dest.sin6_addr.u.Word[2] = htons(addr16[2]);
    bvlc_dest.sin6_addr.u.Word[3] = htons(addr16[3]);
    bvlc_dest.sin6_addr.u.Word[4] = htons(addr16[4]);
    bvlc_dest.sin6_addr.u.Word[5] = htons(addr16[5]);
    bvlc_dest.sin6_addr.u.Word[6] = htons(addr16[6]);
    bvlc_dest.sin6_addr.u.Word[7] = htons(addr16[7]);
    bvlc_dest.sin6_port = htons(dest->port);
    bvlc_dest.sin6_scope_id = BIP6_Socket_Scope_Id;
    debug_print_ipv6("Sending MPDU->", &bvlc_dest.sin6_addr);
    /* Send the packet */
    return sendto(
        BIP6_Socket, (const char *)mtu, mtu_len, 0,
        (const struct sockaddr *)&bvlc_dest, sizeof(bvlc_dest));
}

/**
 * The common send function for BACnet/IPv6 application layer
 *
 * @param dest - Points to a #BACNET_ADDRESS structure containing the
 *  destination address.
 * @param npdu_data - Points to a BACNET_NPDU_DATA structure containing the
 *  destination network layer control flags and data.
 * @param pdu - the bytes of data to send
 * @param pdu_len - the number of bytes of data to send
 * @return Upon successful completion, returns the number of bytes sent.
 *  Otherwise, -1 shall be returned to indicate the error.
 */
int bip6_send_pdu(
    BACNET_ADDRESS *dest,
    BACNET_NPDU_DATA *npdu_data,
    uint8_t *pdu,
    unsigned pdu_len)
{
    return bvlc6_send_pdu(dest, npdu_data, pdu, pdu_len);
}

/**
 * BACnet/IP Datalink Receive handler.
 *
 * @param src - returns the source address
 * @param npdu - returns the NPDU buffer
 * @param max_npdu -maximum size of the NPDU buffer
 * @param timeout - number of milliseconds to wait for a packet
 *
 * @return Number of bytes received, or 0 if none or timeout.
 */
uint16_t bip6_receive(
    BACNET_ADDRESS *src, uint8_t *npdu, uint16_t max_npdu, unsigned timeout)
{
    uint16_t npdu_len = 0; /* return value */
    fd_set read_fds;
    int max = 0;
    struct timeval select_timeout;
    struct sockaddr_in6 sin = { 0 };
    BACNET_IP6_ADDRESS addr = { 0 };
    socklen_t sin_len = sizeof(sin);
    int received_bytes = 0;
    int offset = 0;
    uint16_t i = 0;

    /* Make sure the socket is open */
    if (BIP6_Socket == INVALID_SOCKET) {
        return 0;
    }
    /* we could just use a non-blocking socket, but that consumes all
       the CPU time.  We can use a timeout; it is only supported as
       a select. */
    if (timeout >= 1000) {
        select_timeout.tv_sec = timeout / 1000;
        select_timeout.tv_usec =
            1000 * (timeout - select_timeout.tv_sec * 1000);
    } else {
        select_timeout.tv_sec = 0;
        select_timeout.tv_usec = 1000 * timeout;
    }
    FD_ZERO(&read_fds);
    FD_SET(BIP6_Socket, &read_fds);
    max = BIP6_Socket;
    /* see if there is a packet for us */
    if (select(max + 1, &read_fds, NULL, NULL, &select_timeout) > 0) {
        received_bytes = recvfrom(
            BIP6_Socket, (char *)&npdu[0], max_npdu, 0, (struct sockaddr *)&sin,
            &sin_len);
    } else {
        return 0;
    }
    /* See if there is a problem */
    if (received_bytes < 0) {
        return 0;
    }
    /* no problem, just no bytes */
    if (received_bytes == 0) {
        return 0;
    }
    /* the signature of a BACnet/IPv6 packet */
    if (npdu[0] != BVLL_TYPE_BACNET_IP6) {
        return 0;
    }
    /* pass the packet into the BBMD handler */
    memcpy(&addr.address[0], &(sin.sin6_addr), 16);
    memcpy(&addr.port, &sin.sin6_port, 2);
    offset = bvlc6_handler(&addr, src, npdu, received_bytes);
    if (offset > 0) {
        npdu_len = received_bytes - offset;
        if (npdu_len <= max_npdu) {
            /* shift the buffer to return a valid NPDU */
            for (i = 0; i < npdu_len; i++) {
                npdu[i] = npdu[offset + i];
            }
        } else {
            npdu_len = 0;
        }
    }

    return npdu_len;
}

/** Cleanup and close out the BACnet/IP services by closing the socket.
 * @ingroup DLBIP6
 */
void bip6_cleanup(void)
{
    if (BIP6_Socket == INVALID_SOCKET) {
        return;
    }
    closesocket(BIP6_Socket);
    BIP6_Socket = INVALID_SOCKET;
    WSACleanup();

    return;
}

/**
 * @brief Join a multicast group
 */
void bip6_join_group(void)
{
    struct in6_addr broadcast_address = { 0 };
    struct ipv6_mreq join_request = { 0 };
    int status = 0; /* return from socket lib calls */

    if (BIP6_Socket == INVALID_SOCKET) {
        return;
    }
    /* join a multicast group */
    memcpy(
        &broadcast_address.s6_addr[0], &BIP6_Broadcast_Addr.address[0],
        IP6_ADDRESS_MAX);
    memcpy(
        &join_request.ipv6mr_multiaddr, &broadcast_address,
        sizeof(struct in6_addr));
    /* Let system not choose the interface */
    join_request.ipv6mr_interface = BIP6_Socket_Scope_Id;
    status = setsockopt(
        BIP6_Socket, IPPROTO_IPV6, IPV6_JOIN_GROUP, (char *)&join_request,
        sizeof(join_request));
    if (status < 0) {
        debug_fprintf(
            stderr,
            "BIP6: setsockopt(IPV6_JOIN_GROUP) failed "
            "with error %d: %s\n",
            WSAGetLastError(), PrintError(WSAGetLastError()));
    }
}

/**
 * @brief Leave a multicast group
 */
void bip6_leave_group(void)
{
    struct in6_addr broadcast_address = { 0 };
    struct ipv6_mreq leave_request = { 0 };
    int status = 0; /* return from socket lib calls */

    if (BIP6_Socket == INVALID_SOCKET) {
        return;
    }
    /* leave a multicast address */
    memcpy(
        &broadcast_address.s6_addr[0], &BIP6_Broadcast_Addr.address[0],
        IP6_ADDRESS_MAX);
    memcpy(
        &leave_request.ipv6mr_multiaddr, &broadcast_address,
        sizeof(struct in6_addr));
    status = setsockopt(
        BIP6_Socket, IPPROTO_IPV6, IPV6_LEAVE_GROUP, (char *)&leave_request,
        sizeof(leave_request));
    if (status < 0) {
        debug_fprintf(
            stderr,
            "BIP6: setsockopt(IPV6_LEAVE_GROUP) failed "
            "with error %d: %s\n",
            WSAGetLastError(), PrintError(WSAGetLastError()));
    }
}

/** Initialize the BACnet/IP services at the given interface.
 * @ingroup DLBIP6
 * -# Gets the local IP address and local broadcast address from the system,
 *  and saves it into the BACnet/IPv6 data structures.
 * -# Opens a UDP socket
 * -# Configures the socket for sending and receiving
 * -# Configures the socket so it can send multicasts
 * -# Binds the socket to the local IP address at the specified port for
 *    BACnet/IPv6 (by default, 0xBAC0 = 47808).
 *
 * @note For Windows, ifname is the IPv6 address of the interface.
 *
 * https://msdn.microsoft.com/en-us/library/windows/desktop/ms738639(v=vs.85).aspx
 *
 * @param ifname [in] The named interface to use for the network layer.
 *
 * @return True if the socket is successfully opened for BACnet/IPv6,
 *         else False if the socket functions fail.
 */
bool bip6_init(char *ifname)
{
    WSADATA wd;
    int RetVal;

    /* Ask for Winsock version 2.2. */
    if ((RetVal = WSAStartup(MAKEWORD(2, 2), &wd)) != 0) {
        debug_fprintf(
            stderr, "BIP6: WSAStartup failed with error %d: %s\n", RetVal,
            PrintError(RetVal));
        WSACleanup();
        exit(1);
    }
    if (BIP6_Addr.port == 0) {
        bip6_set_port(0xBAC0U);
    }
    if (BIP6_Debug) {
        debug_fprintf(
            stderr, "BIP6: IPv6 UDP port: 0x%04X\n", (unsigned)BIP6_Addr.port);
    }
    bip6_set_interface(ifname);
    if (BIP6_Broadcast_Addr.address[0] == 0) {
        bvlc6_address_set(
            &BIP6_Broadcast_Addr, BIP6_MULTICAST_LINK_LOCAL, 0, 0, 0, 0, 0, 0,
            BIP6_MULTICAST_GROUP_ID);
    }
    if (BIP6_Socket == INVALID_SOCKET) {
        debug_fprintf(
            stderr, "BIP6: Fatal error: unable to serve on any address.\n");
        WSACleanup();
        exit(1);
    }

    return true;
}
